Seasonal and Spatial Evaluation of Euphrates River Water Quality Using Chemical and Physical Indicators and Multivariate Analysis in Karbala, Iraq

The increased demand for water for both private and public use as the population grows. However, human activities have contributed to a decline in water quality. The objective of this study was to evaluate the water quality of the Euphrates River. Samples of water were gathered at four distinct places of the Euphrates River throughout the rainy and dry seasons of 2023/2024. Standard techniques were used to analyze twelve physical-chemical water quality parameters: water temperature, air temperature, electrical conductivity, hydrogen ion concentration, total dissolved solids, salinity, total suspended solids, dissolved oxygen, turbidity, biological oxygen demand 5, total phosphorus, and total nitrogen. Certain parameters, including water temperature, turbidity, total dissolved solids, biological oxygen demand, total phosphorus, and total nitrogen, exceeded the recommended limits. Several variables showed a statistically significant variation between the sampling seasons. Regarding the study sites, the findings showed notable variations in total dissolved solids, turbidity, total suspended solids, and hydrogen ion concentration. Water temperature-air temperature, total dissolved solids-electrical conductivity, electrical conductivity-Salinity, turbidity-total phosphorus, Salinity-total dissolved solids, and turbidity-total suspended solids show a strong positive association (P ˂ 0.01), whereas water temperature-dissolved oxygen, hydrogen ion concentration-total phosphorus, and hydrogen ion concentration-total nitrogen show substantial negative correlations (P ˂ 0.01). According to principal components analysis, there was a stronger correlation between air temperature, water temperature, biological oxygen demand and hydrogen ion concentration during the dry period. Based on hierarchical clustering, air temperature and Dissolved Oxygen were the most divergent, while electrical conductivity and salinity were the most similar. The Euphrates River's degradation is highlighted in this study, underlining the urgency of taking action to preserve this essential resource for present and future generations.